Process for oxidizing olefins to aldehydes and ketones



United States Patent 3,110,?74 PROCESS F03 (EXHDHZHNG ()LEFINS T0 ALDEHYDES AND KETDNES Emmerich Faszthory and Wilhelm Riemcnschneider, Franlrfiurt am Main, Germany, assignors to Farbwerhe Hoechst Alrtieugeseilschatt, vormals Meister Lucius & Bruning, Frauln'urt am Main, Germany, a corporation oi Germany No Drawing. Filed Nov. 30, 1959, Ser. No. 855,975 Claims priority, application Germany Nov. 29, 1953 5 Claims. (Cl. 2&0-59'7) The present invention relates to a process for oxidizing olefins to aldehydes, ketones and acids.

It is described, for example, in U.S. patent applications Serial Nos. 747,115 and 747,116 both filed July 8, 1958; Serial No. 768,624 filed October 21, 1958; Serial No. 770,007 filed October 28, 1958 and now Patent No. 3,076- 032; Serial Nos. 769,912 and 769,554 both filed October 27, 1958 and 769,554 is now abandoned; Serial Nos. 788,488 filed January 23, 1959 and 803,096 filed March 31, 1959, to oxidize ethylene or other olefins such as propylene, butylene, isobutylene or pentene to the corresponding aldehydes, ketones and acids by means of oxygen or gases containing oxygen in the presence of redox systems and noble metals or noble metal compounds forming complex compounds with ethylene.

On carrying out these processes it has been found that optimum yields are obtained with the use of palladium or compounds thereof. For the oxidation of ethylene to acetaldehyde, for example, there are preponderantly used catalysts containing palladium chloride and copper chloride. With catalysts of this kind, a certain amount of palladium metal may occasionally separate out in the reaction vessel, for example, due to an operating error. The precipitate generally forms a thin layer (mirror) on the wall of the vessel and can be redissolved only with great difiiculty by the catalyst solution after a certain time of ageing. The precipitate may also deposit in recesses and corners of the apparatus, for example at flanged joints or pipe bends which have only little contact with the catalyst current so that here, too, redissolution is only very slow. A more or less large portion of the palladium compound used may therefore be present in the metallic state and does no longer participate in the reaction, thus decreasing the extent of conversion and the space-time yield.

The present invention is based on the observation that the aforesaid disadvantages can be avoided by adding to the liquid or solid catalyst containing palladium small portions of compounds of metals which according to the electromotive series are nobler than palladium, for example compounds of gold or platinum or mixtures of these compounds. The amount in which the substances are added, calculated as metal, generally ranges from 0.01 to 5%, and advantageously 0.5 to 1% of the palladium present but may be outside this range if desired. It is of no consequence to which anions or elements, for example oxygen, the additives are bound provided that they are soluble under the reaction conditions applied. In this manner, precipitation of metallic palladium in the reaction vessel is avoided or any possible precipitates are redissolved after a short time and the total extent of conversion, considered over a prolonged time, is increased.

Since compounds of gold or platinum, too, react with oleiins with separation of metal, so-calle-d local elements are probably formed with the simultaneously precipitated palladium metal, which local elements me much more readily soluble in the acid catalyst solution containing oxygen than the pure metals. This could not be foreseen since the carbonyl compounds formed, for example acetaldehyde, acetone or methyl ethyl ketone, which are contained in the catalyst solution strongly hinder the dissolution. It is known from literature that aldehydes and ketones greatly inhibit the dissolution of metal precipitates; acetaldehyde and acetone are even described as inhibitors. it is furthermore surprising that the precipitation of cuprous chloride, which substantially always precedes the metal separation, is largely suppressed by the process of the present invention so that in a plant operated according to the invention working troubles are less liable to occur than is the case when catalysts not containing these additional noble metals are used.

T he aforesaid measures are also applicable when catalysts in a solid state are used, in which case reactions leading to the formation and dissolution of metal may also occur in the presence of water vapor, a process described in the aforesaid patent application Ser. No. 747,115.

The process of the present invention is carried out in the presence of water, palladium compounds and redox systems which advantageously still contain copper salts. The redox systems may contain, instead of or besides copper compounds, compounds of metals which, under the reaction conditions can exhibit several oxidation stages and are at least monovalent in the reduced stage. Coinpounds of this kind are, for example, compounds of mercury, cerium, thallium, tin, lead, titanium, vanadium, antimony, chromium, molybdenum, uranium, manganese, iron, cobalt and nickel.

As anions there may be used, for example, halogen ions such as bromine ions, and advantageously chlorine ions or chlorate, perchlorate, nitrate or mixtures of such anions with sulfate radicals or acetate radicals.

it is of special advantage to use catalysts which contain iron, chromium, manganese and/or cerium compounds in addition to palladium and copper compounds. in many cases it is suihoient to use a ratio oi": copperzpalladium of above 10:1, for example above 15:1, and advantageously up to :1 or snore, for example 50 to 500:1.

In another advantageous form of the present invention, catalysts containing chlorine ions are used and further anions, advantageously chlorine ions, are added during the reaction, for example, in the form of hydrogen chloride or compounds yielding chlorine ions such as acetyl chloride, ethyl chloride, tertiary butyl chloride or brornotrichloride. In this case, the ratio of copperzchlorine is advantageously in the range of 1:1 to 1:3, and preferably 1:1.4 to 122.5.

The pH is advantageously within the range of 0.8 to 5; it may, however, be outside this range, for example 0.5, if desired. The process is advantageously carried out at a temperature within the range of 50 to 160 C.; higher or lower temperatures may, however, be applied. When operating, tfOI example, ina flow tube, temperatures up to 250 C., and preferably from to 220 C. may be applied. The process may be carried out under atmospheric pressure, elevated pressure or reduced pressure, for example, under a pressure up to 100 atmospheres gage, and advantageously up to 50 atmospheres gage. Pressure maybe applied as well when working at a temperature above 100 C. as at a temperature below 100 C. At a temperature above 100 C., it is necessary to apply pressure or to add substances which raise the boiling point. It may furthermore be of advantage to add a salt regardless of the temperature applied. As salts there may be used, for example, the chlorides or acetates of lithium, sodium, potassium, ammonium, calcium, barium, magnesium or zinc; FeC-l or salts of the named elements with other anions. In the case of liquid catalysts, additional solvents containing hydrophilic groups may concomitantly be used, for example acetic acid,

ethylene glycol, propylene glycol, glycerol or clioxan or mixtures of these substances.

The process of the invention can be used for converting ethylene into acetaldehyde and acetic acid and also for converting higher olefins such as propylene, buty-lenes and pentenes. Propylene, for example, yields preponderantly acetone and propionaldehyde; the butylenes yield methylethylketone, butyraldehyde or isobutyraldehyde and butadiene yields diacetyl and croton aldehyde.

As oxidizing agent oxygen is predominantly used, if desired in the form of air or air enriched with oxygen. The reactants may be used in a pure state or in the form of gas mixtures; they may be premixed or introduced through one or more inlets which may be disposed one after the other in the direction of flow. To the olefins there may be added, for example, saturated aliphatic hydrocarbons such as methane, ethane, propane, butane, isobutane, higher saturated aliphatic compounds, cyclohexane, benzene, toluene, nitrogen, carbon dioxide, carbon monoxide or hydrogen which are at most partially attacked by the catalysts to be used in the process of the invention or any desired mixtures thereof.

The process of the invention may be carried out in various ways, for example in a flow tube as described in US. applications No. 769,554 and No. 848,531 filed October 26, 1959, and now abandoned and may be combined with the measures described in the earlier specifications. Quiescence vessels may be allotted, for example, to the reactors in which quiescence vessels the gaseous and liquid phase separate (see the aforesaid patent application Ser. No. 769,912). Furthermore, the process may be carried out in one stage in a reaction vessel or in two stages whereby the second stage may be carried out in the same or another reaction vessel. The two-stage process may also be carried out in a manner such that a small portion of the oxygen is already introduced in the first stage and the remainder is used in the second stage for regenerating the catalyst. When proceeding in this manner, the ratio of olefin:oxygen in the first stage is advantageously at least 2.5: 1, and preferably at least 6:1. In the two-stage process, the catalyst may be regenerated under known conditions, for example at a temperature within the range of 50 to 150 C., and even at pressures and/ or temperatures which are different from the reaction conditions used. When operating in two stages, air is advantageously used as oxidizing agent for the catalyst regeneration.

It is furthermore possible to carry out the reaction under the action of active radiation, particularly ultraviolet light. In this case it is particularly advantageous to expose the oxygen or catalyst near the oxygen inlet to rays. By an appropriate adjustment of the temperature and pressure and by choosing a suitable amount of olefin, the olefin can be converted substantially completely in one passage.

The following examples serve to illustrate the invention but they are not intended to limit it thereto.

Example 1 (a) A tube in upright position was used which was charged with 1 liter of a catalyst containing, per liter water, 3 grams PdCl 120 grams CuCl .2H O. Into said tube 40 liters ethylene and liters oxygen were introduced per hour through a frit. The working temperature was 80 C. After 5 hours, considerable precipitation of cuprous chloride occurred. Shortly thereafter a thin layer of palladium deposited on the glass wall and the conversion to :acetaldehyde decreased rapidly.

(b) The process was carried out as described (sub 1a) with the exception that mg. AuCl were added to the 4. fresh catalyst. Cuproue chloride precipitated only after 7 hours. No palladium separated out. The catalyst retained its activity and the cuprous chloride precipitate dissolved on its own accord after some time.

Example 2 (a) When the process was carried out under the conditions described in Example 1 in the presence of a catalyst having the same composition as that described in Example 1, but while using a coarser inlet rrit, cuprous chloride was precipitated after 2 hours and soon thereafter a thin layer of palladium formed on the wall. The conversion -was thereby reduced from 30% to about 5%.

(b) When the process was carried out as described in Example 2a, but while adding 60 mg. PtCl, to the catalyst, cuprous chloride precipitated only after 3 hours, while the same extent of conversion was obtained. Within the next 3 hours no thin layer of palladium formed.

Example 3 40-1iters ethylene and 10 liters oxygen were introduced per hour into a catalyst having a temperature of C. and containing, per liter water, 3 grams PdCl grams CuCI ZH O and 60 grams Ce(SO .4H O. The catalyst opyated satisfactorily for about 2 days, then cuprous chloride continuously precipitated. A thin layer of palladium also formed. At intervals of about 1 hour the cuprous chloride and the palladium layer were dissolved by interrupting the ethylene introduction and blowing-in pure oxygen. After the addition of 15 mg. PLCL, to the catalyst, the process proceeded without precipitation to cuprous chloride or palladium. A smal amount of cuprous chloride precipitated again only after a further 7 hours. After a short time, however, the precipitate dissolved of itself.

We claim:

1. A process for the conversion of an olefinic hydrocarbon to a carbonyl compound selected from the group consisting of aldehydes and ketones by oxidation of an oiefinic carbon atom of said olefinic hydrocarbon to a carbonyl group, which process consists essentially of contacting said olefinic hydrocarbon and oxygen in a neutral to acid medium with water and a catalyst of (a) a salt of palladium, and '(b) as a redox system, an inorganic salt of a metal showing several valence states under the reaction conditions applied, said contacting taking place in the presence of from 0.01 to 5 percent, calculated as metal and refered to the weight of palladium present, of an ion or" a metal selected from the group consisting of gold and platinum.

2. A process as. in claim 1 wherein the metal ion is present in said catalyst in amount of from 0.5 to l percent, calculated as metal and referred to the weight of palladium present.

3. A process as in claim 1 wherein said metal showing several valence states under the reaction conditions applied is copper.

4. A process as in claim 1 wherein said ion is gold ion.

5. A process as in claim 1 wherein said ion is platinum lOIl.

References Cited in the file of this patent FOREIGN PATENTS France Mar. 1, 1944 Germany Nov. 14, 1941 OTHER REFERENCES 

1. A PROCESS FOR THE CONVERSION OF AN OLEFINIC HYDROCARBON TO A CARBONYL COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALDEHYDES AND KETONES BY OXIDATION OF AN OLEFINIC CARBON ATM OF SAID OLEFINIC HYDROCARBON TO A CARBONYL GROUP, WHICH PROCESS CONSISTS ESSENTIALLY OF CONTACTING SAID OLEFINIC HYDROCARBON AN OXYGEN IN A NEUTRAL TO ACID MEDIUM WITH WATER AND A CATALYST OF (A) A SALT OF PALLADIUM, AND (B) AS A REDOX SYSTEM, AN INORGANIC SALT OF A METAL SHOWING SEVERAL VALENCE STATES UNDER THE REACTION CONDITIONS APPLIED, SAID CONTACTING TAKING PLACE IN THE PRESENCE OF FROM 0.01 TO 5 PERCENT, CALCULATED AS METAL AND REFERRED TO THE WEIGHT OF PALLADIUM PRESENT, OF AN ION OF A METAL SELECTED FROM THE GROUP CONSISTING OF GOLD AND PLATINUM. 